The present invention relates to a display control apparatus for providing a plurality of color element data signals at a display unit having an interface coupled to binary video signal lines.
A conventional color display monitor used as a standard terminal device of a personal computer or the like has an interface coupled to three video signal lines for transmitting color element data signals of R (red), G (green) and B (blue) in the form of binary data. Since only a data signal of logic "0" or "1" is supplied to each of the signal lines, a multicolor display of a maximum of 8 colors (2.sup.3) can be performed with the R, G and B color signals.
A conventional personal computer which allows multicolor display of 8 or more colors is already commercially available. However, in this case, a standard display monitor having an interface with binary color signal lines cannot be used. In order to perform multicolor display of more than 8 colors, a video signal line for transmitting the luminance signal may be added. In this case, a luminance signal of logic "1" represents high luminance, and a luminance signal of logic "0" represents low luminance, thereby providing a 16-color display. Alternatively, three video signal lines of R, G and B color elements are added to provide 4-level gradation of each color element, thereby providing a 64-color display. In addition to these arrangements, the video signal is converted to an analog signal to transmit luminance data in accordance with the magnitude of the analog signal. However, these conventional methods require a color display monitor having a special interface and a signal cable compatible with this special interface.